Stringed musical instrument neck incorporating automatic warp and bow prevention means



United States Patent 1 13,535,975

[72] Inventor Paul Daniel Broussard [56] References Cited Andrew,Muisiana (1009 Hebe", UNITED STATES PATENTS 2,335,244 11/1943 Gugino84/293 P 68,268 2,497,116 2/1950 Dopyera.... 84/293 [22] Oct-@19693,418,876 12/1968 Dopyera 84/293 Continuation-impart of application Ser.No. 724,902, April 29, 1968, abandoned.

[45] Patented Oct. 27, 1970 [54] STRINGED MUSICAL INSTRUMENT NECKINCORPORATING AUTOMATIC WARP AND BOW Primary Examiner-Richard B.Wilkinson Assistant Examiner-John F. Gonzales ABSTRACT: Basically, in astringed musical instrument having a neck pivotably connected to theinstrument body, the

improvement comprising, a neck height adjustment means' PREVENTION MEANS10 Claims, 8 Drawing Figs.

[51] Int.Cl Gl0d3/00 [50] Field of Search 84/293 been such that neckbowing and warping in some instances was not controlled at all, while inother instances the neck incorporated a truss rod or rods which requiredperiodic manual adjustment after having been preset at the factory, thusin such a case the periodic manual adjustments have to be made by trialand error with no guarantee of precise adjustment. If such prior trussrod or rods are overtightened this either causes neck warping and bowingor breakage of the internal truss rod. Furthermore, if such prior trussrod or rods are not capable of being adjusted the neck will warp and bowexcessively. In addition, prior art warp and bow prevention means arenot self-adjusting thus susceptible to substantial improvement.

It is an object of the present invention to provide an automaticallyself-adjusting neck bow and warp prevention means to control and preventexcessive neck bending, warping, and bowing.

In the drawings:

FIG. 1 is a face plan view of an instrument incorporating the presentinvention;

FIG. 2 is a side view of an instrument incorporating the presentinvention;

FIG. 3 is a back plan view of an instrument incorporating the presentinvention;

FIG. 4 is a face plan view of an instrument body incorporating thepresent invention;

FIG. 5 is a back plan view of an instrument neck incorporating thepresent invention;

FIG. 6 is an enlarged fragmentary transparent side view of an instrumentincorporating the present invention;

FIG. 7 is an enlarged fragmentary sectional view taken substantiallyalong line 4-4 in FIG. 6; and

FIG. 8 is an enlarged fragmentary sectional view taken substantiallyalong line 5-5 in FIG. 6.

Referring to the drawings, the present invention shown in FIGS. 1 and 2incorporates a body 10, a neck 11, tuning keys 12, strings 13, a bridge14, a tailpiece 15, pickups l6 and 17, controls 18, 19, and 20, a jack21, and switches 22 and 23. The instrument back 24 is shown in FIGS. 2and 3 while the instrument sides 25 are shown in FIG. 2. The shoulderstrap buttons 26 and 27 are shown in FIGS. 1, 2, and 3.

The instrument neck 11 shown in FIGS. 1, 2, 3, 5, 6, 7, and 8 is mountedto the instrument body 10 by a hinge 28 shown in FIGS. 2, 3, 4, 5, 6,and 8. One half of the hinge 28 shown in FIG. 5 is mounted to the neck11 with the mounting screws 29, 30, and 31 while the other half of themounting hinge 28 shown in FIG. 4 is mounted to the instrument body 10with the mounting screws 32, 33, and 34, and the neck 11 is held inplace by the hinge pin 35 which is shown in FIG. 4. It is emphasizedthat the hinge pin 35 relationship to the hinge 28 should be precisionfitting, that is a precise and close tolerance fit, so that the hinge 28will swivel only in the direction it is manufactured to swivel. Ifotherwise this allows a slight shift which in turn may cause inaccuratestring vibration or string detuning. Furthermore, with the presentspecific example and the present stringed instrument tuning tension suchas for a standard guitar, the hinge 28 should be no less than a fullonesixteenth of an inch thick or more such as of plated steel or ofequivalent strength, otherwise if the hinge strength is belowrequirements the hinge 28 will bend with and due to the applied stringtension.

Due to the string pull caused by tensioned strings 13 causes neckwarping and bowing as well known in the art, thus the present inventionutilizes preferably a cylindrical truss rod 36 which is embedded in arouted groove or channel provided for such purpose between the fingerboard 37 and the neck base 42 as shown in FIGS. 5, 6, 7, and 8. At oneend of the truss rod 36 nearest the tuning keys 12 the rod 36 may bestraight or preferably bent at an angle. This angle bend in the rod 36indicated by dashed line 38 in FIGS. 6 and 7 is not critical thus may beany angle such as from 2 to from parallel to the longitudinal axis ofthe surface of the fretboard 37, and preferably the rod 36 should have aslight curve and are along its length similar to that indicated bydashed line 38 but producing a lesser angle and curve, while near theother end of the truss rod 36 nearest the end of the neck 11 preferablyshould be bent approximately 90 from parallel to the longitudinal axisof the surface of the fretboard 37 as showniin FIGS. 6 and 8. Thisapproximate 90 bend is indicated by 39in FIGS. 6 and 8, at which pointthe end of the truss rod 36 traverses the neck base 42 and terminatesfitting into the hole provided in the supporting and stopping threadedmember 40, but the rod 36 does not thread into the supporting member 40.Instead, the truss rod 36 fits into the hole drilled or formed into thesupporting and stopping member 40 as shown in FIGS. 6 and 8. The trussrod supporting and stopping threaded member 40 threads into theinstrument body 10 and is inserted through the gear insert member 41which is pressed into the body 10 to prevent raw wood edge as well asprovide a screwdriver guide for neck height adjustment. It isemphasized, the truss rod supporting and stopping member 40 in FIGS. 6and 8 is provided for neck height adjustment and is not a manualadjustment of the rod 36 nor a manual adjustment of the tension to beimposed upon the rod 36 as is required in prior art.

It is also of utmost importance and greatly emphasized, the groove orchannel between the fingerboard 37 and the neck base 42 provided for thetruss rod 36 to be inserted and embedded therein has to have free playas apparent in FIGS. 6, 7, and 8. That is a slight clearance between therod 36, the fingerboard 37 and the neck base 42. Thus the said groove orchannel embedding the said rod is to be slightly larger than the trussrod 36. Therefore, so that the glue used to glue the fingerboard 37 tothe neck base 42 does not adhere to the rod 36, the rod 36 preferablymay be insulated by fitting the rod 36 into a thin plastic tubing orcoating such as Teflon tubing or the rod 36 may be coated with heavygrease such as axle grease prior to placing the rod 36 into position andpermanently embedding it between the fingerboard 37 and the neck base42. If the rod 36 is not free to move slightly along its entire lengthlet it be clearly understood that the rod 36 in such a case will notfunction properly or may not function at all.

An exact 90 bend in the rod 36 near the end of the neck 11 indiwted by39 in FIGS. 6 and 8 is again not a precise requirement. In fact, the rod36 may be bent at other angles such as illustrated by dashed line 43 inFIG. 6 which represents an approximate 70 angle from the longitudinalaxis of the strings 13.

The rod 36 shown in FIGS. 6, 7, and 8 may be of any suitable materialwhich will withstand the applied string pressure, but has to be soft andflexible enough to bend, conform to the aforesaid groove or channel, andfree to move alongits length, such as of preferably soft steel or brass.A specific size which may be used for example may be approximatelythree-thirtyseconds of an inch in diameter. Furthermore, the rod 36preferably may be weakened, such as by scoring in the general area ofthe 90 bend 39 in FIGS. 6 and 8 to reduce the pressure required to causethe rod 36 to move forwards. In fact, in such a case a larger diameterrod may then be used.

In the operation of the neck 11 shown in FIG. 5, the neck 1 may bemounted, removed, replaced, or exchanged with the hinge pin 35 shown inFIG. 4 while the height of the neckll may be adjusted by application ofa screwdriver to the slot provided in the truss rod supporting andstopping threaded member 40 shown in FIGS. 6 and 8.

Shown in FIG. 6, as the tension is applied to the strings l3 such as bythe tuning keys 12 this causes a corresponding tension upon the neck 11,causing the neck 11, the neck mounting hinge 28, and the rod 36 toswivel in the direction of the supporting and stopping threaded member40, however the truss rod supporting and stopping threaded member 40stops the rod 36 from swiveling thereby causing a corresponding equalcounter tension, pressure, and force to be exerted and applied to therod 36 along its entire length back to the tip of the rod 36 bent at anangle indicated by dashed line 38 in FIGS. 6 and 7 thus a correspondingself-adjusting counter tension, pressure, and force is internallyexerted upon the neck .11 in opposition to the applied string tensionfor controlling and preventing excessive longitudinal distortion of theneck i 11 along the length of the fingerboard 37.

It is tobe understood, regardless of the method of bow and warpprevention, any neck may bow very slightly. in fact, any neck should beallowed to bow slightly to enable lower string clearance and reducestring rattle or hiss, as well known in the art. Thus by automaticallyself-adjusting warp and bow prevention means, it is meant any neck whichautomatically self-adjusts to compensate, counteract, and equalizestring pull to thereby keep the instrument neck true to practical limitswhereby the neck does not become bowed nor warped to the point ofrequiring excessive string clearance, thus not to be limited to anabsolutely true instrument neck.

It is also to be understood and apparent that the present invention maybe applied to semihollow body type, hollow body type, flat top type,arched type, accoustic type, electric type, as well as right-orleft-handed instruments. Furthennore, it is also apparent that theinstrument neck may be mounted to an instrument body countersunken inthe instrument body as practiced in the art, that is mounting the neckto the instrument body in such a manner that only part of the neckextends above the surface of the top of the instrument body.

The foregoing is considered as illustrative of the principals of theinvention, further, since numerous modifications and changes may readilyoccur, it is not desired to limit the invention to the exactconstruction and operation shown and described. Thus all suitablemodifications and equivalents may be resorted to without falling beyondthe scope of the present invention.

1 claim:

1. In a stringed musical instrument having connected to the instrumentbody, mg:

a neck height adjustment means mounted within' said body;

a truss rod loosely secured within a channel in'said neck;

and having one end terminating against said neck height adjustment meanswhereby said adjusting means and said truss rod are movable to vary theforce acting agaihstsaid neck in order to prevent neck warping andbowing, and at the same time for controlling the height of said neck.

2. The invention specified in claim 1 wherein the neck height adjustmentmeans comprises a threaded member threading into the instrument body.

3. The invention specified in claim 1 wherein said truss rod is bentnear the end of said neck nearest the instrument bridge.

4. The invention specified in claim 3 wherein said truss rod is bentwithin a range from parallel to from parallel to the longitudinal axisof the fingerboard.

5. The invention specified in claim 1 wherein said truss rod is curvedalong its length.

6. The invention specified in claim 5 wherein said truss rod a neckpivotably the improvement comprisis bent along its length within a rangefrom parallel to less than

